Process for the preparation of unsaturated fatty alcohols

ABSTRACT

PROCESS FOR THE PREPARATION OF UNSATURATED FATTY ALCOHOLS BY SELECTIVE HYDROGENATION OF UNSATURATED FATTY ACIDS AND ESTERS THEREOF WITH ALIPHATIC ALCOHOLS AT 250-330*C. AND HYDROGEN PRESSURE OF 100-500 ATMOSPHERES, THE AMOUNT OF HYDROGEN BEING 10-100 NM.3 PER LITER OF STARTING MATERIAL, IN PRESENCE OF ZINC-ALUMINUM OXYGEN CONTAINING A CATALYST REDUCTIVELY PRETREATED AT ELEVATED TEMPERATURES.

United States Patent F Int. (:1. C07c 59/00, 33/02 US. Cl. 260-638 A 8Claims ABSTRACT OF THE DISCLOSURE Process for the preparation ofunsaturated fatty alcohols by selective hydrogenation of unsaturatedfatty acids and esters thereof with aliphatic alcohols at 250-330 C. andhydrogen pressure of 100-500 atmospheres, the amount of hydrogen being10-100 Nmfi per liter of starting material, in presence of zinc-aluminumoxygen containing a catalyst reductively pretreated at elevatedtemperatures.

REFERENCE TO RELATED APPLICATION This application is acontinuation-impart of application entitled Process for the Preparationof Unsaturated Alcohols, bearing a Ser. No. 561,042 which was filed onJune 28, 1966, now abandoned.

STATE OF THE ART The preparation of unsaturated fatty alcohols by highpressure hydrogenation of unsaturated fatty acids and esters thereof inliquid or gaseous phases with specific, selective active catalysts iswell known. Ullmans Encyklopiidie der technischen Chemie (3rd edition,vol. 7, 1956, page 443), states that the preferred catalysts for thishydrogenation are zinc and cadmium containing catalysts such as Zinccarbonates, zinc chromites, zinc vanadate, zinc-cadmium chromite,cadmium-copper carbonate, etc. German Pat. No. 865,741 discloses thepreparation of unsaturated fatty alcohols by hydrogenation ofunsaturated fatty acids or their esters or anhydrides with mixedcatalysts containing vanadate in addition to zinc or cadmium. The saidcatalysts are formed in the usual manner by stirring zinc oxide orcadmium oxide together with ammonium vanadate in the presence of water,drying the resulting mixture and forming tablets or pellets from thedried powder which are then used for the hydrogenation without furtherprocessing. Bertsch et al. in Fette, Seifen, Anstrichmittel (vol. 66,1964, pp. 763-773), have compiled a review of selectively activehydrogenation catalysts and combinations thereof. However, allpreviously known catalysts have the disadvantage that during thehydrogenation the double bonds of the starting materials areincompletely retained and/or an undesirable transposition of the cisform of the double bonds into the trans form occurs.

OBJECTS OF THE INVENTION It is an object of the invention to provide anovel processed for the preparation of unsaturated fatty alcohols byselective hydrogenation of unsaturated fatty acids and esters thereof.

It is another object of the invention to provide novel catalysts for theselective hydrogenation of unsaturated fatty acids and esters thereof.

These and other objects and advantages of the inven- "ice tion willbecome obvious from the following detailed description.

THE INVENTION The novel process of the invention for the preparation ofunsaturated fatty alcohols of 8 to 22 carbon atoms by the continuousselective hydrogenation of unsaturated fatty acids and esters thereofcomprises hydrogenating a member selected from the group consisting ofunsaturated fatty acids of 8 to 22 carbon atoms and their esters withmonovalent aliphatic alcohols of 1 to 18 carbon atoms at temperatures of250 to 330 C. and a hydrogen pressure of to 500 atmospheres in thepresence'of zinc-aluminum catalyst which has been pretreated at 400 to1000" C. in a reducing atmosphere, the amount of hydrogen being 10 to100 Nm. per liter of starting material. The pretreatment of the catalystis preferably effected at 500 to 900 C.

The hydrogenation of unsaturated fatty acids with single bond and theiresters With the pretreated catalysts of the invention retains not onlythe double bond but also the cis configuration. The pretreated catalystsof the invention are considerably superior in their selectivity forretaining the double bond to the best known prior art catalysts whichare zinc-chromium catalysts which have been pretreated at 280 to 350 C.in a reducing atmosphere. The excellent activity of the catalysts of theinvention is all the more unexpected because one skilled in the artwould expect the pretreatment at red heat to cause the catalysts tosinter together with a loss of surface area and catalytic activity.

The unsaturated fatty acids of 8 to 22 carbon atoms may be monoorpolyunsaturated and commonly occur in natural fats and oils such as palmkernel oil, palm oil, olive oil, peanut oil, rapeseed oil, etc. Examplesof suitable acids are oleic acid, linoleic acid, linolenic acid,ricinoleic acid, A -decylenic acid, M-dodecylenic acid, parinaric acid,arachidonic acid, S-eicosenic acid, etc.

Examples of suitable monovalent aliphatic alcohols of 1 to 18 carbonatoms for esters of the said fatty acids are methanol, ethanol,propanol, isopropanol, butanol, tert.- butanol, hexanol, octanol,decanol, dodecanol, oleyl alcohol, etc. Readily volatile fatty esters ofalcohols of 1 to 4 carbon atoms are preferred and particularly themethyl esters are preferred. Mixtures of the unsaturated fatty acids andtheir esters may be used and saturated fatty acids and esters may alsobe present therein.

The zinc-aluminum catalysts can be prepared by admixing powdered zincoxide with an aqueous suspension of amorphous or crystalline aluminumhydroxide or 'y-aluminum oxide. Particularly active catalysts areobtained with freshly precipitated aluminum hydroxide.

For the hydrogenation, the catalysts are preferably used in pellet ortablet form. Therefore, the aqueous paste of the catalyst components isdried and pulverized in the usual manner. If desired, bonding agentssuch as graphite can be admixed with the catalyst powder and the powderis then pressed into pellets for easy handling.

The pretreatment of the catalysts comprises heating the catalysts at 400to 1000 0., preferably 500 to 900 C., in a reducing atmosphere for 1 to10 hours, preferably at atmospheric pressure although pressures aboveatmospheric pressure may be used. The reducing atmosphere may be anyreducing atmosphere such as hydrogen, which is preferred, carbonmonoxide or mixture thereof such as water gas. A reducing atmosphereconsisting essentially of carbon monoxide and hydrogen can be preparedwith methanol vapors.

However, if the same procedure were followed except for the use of theprior art reducing temperatures of 280 to 350 C., the catalysts obtainedare less selective in the hydrogenation of the fatty acids and estersthereof with a"higher de'greeof saturation and isomerization of thedouble bonds. Zinc-aluminum catalysts which are reduced at the lowtemperatures of the prior art or rereduced at high temperatures werefound to be unsuitable 4 -The fatty' esters were hydrogenated withcatalyst-A'in a known hydrogenation apparatus consisting of a 1 litercapacity pressure vessel heated to the desired hydrogenation and filledwith 800 ml. of the catalyst tablets,

0. Commercial linseed-alcohol mixture for the preparation of unsaturatedfatty acids and esters water condenser and means for releasing thepressure to thereof and result in olefins and only slightly unsaturatedseparatethe hydrogen and to recover the reaction prodfatty alcohols.ucts. The methyl esters to be hydrogenated mixed with A preferred modeof the process of the invention for methanol in a 1:2 ratio werepreheated to about 230 C. the preparation of fatty alcohols compriseshydrogenating and then fed to the pressure vessel at'a rate of'200 ml.fatty acids or the esters with monovalent aliphatic alcoper hour througha fluid pipe simultaneously with 4 Nm. hols of 1 to 4 carbon atoms,preferably the methyl esters, per hour of hydrogen preheated to about230 C. under in the presence of monovalent aliphatic alcohols of l to 4250 atmospheres pressure. After passing through the carbon atoms,particularly methanol. With the use of the pressure vessel and the watercondenser, the raw hydroconsidera-ble excess of hydrogen, sufiicientaddition of genation mixture was passed to the pressure releasingaliphatic alcohols of 1 to 4 carbon atoms and the said means where 4 Nm.per hour of hydrogen was released temperature and pressure conditions,the reaction is suband distilled off. The resulting mixture of methanoland stantially effected in the vapor phase when the fatty acidunsaturated fatty alcohols were freed of methanol by first esters ofmonovalent aliphatic alcohols of 1 to 4 carbon distillation atatmospheric pressure and then under wateratoms are the startingmaterials. The result is clear fatty jet vacuum and the fatty alcoholsreceived Were analyzed alcohols free from catalyst contamination. forthe values in Table I.

TABLEII Percent of Hydrosolidifigenation cation Conjutempera- Hydroxypoint, Hydro- Transgated Final products ture, C. LN. S.N. number C.carbons isomer dienes a. Commercial oleyl alcohol 276 92. 6 1. 3 214 10.36 6 1. 21 b. Commercial soya-alcohol mixture 276 140 1A 216 15 0.1911 11.5 0. Commercial linseed-alcohol mixture 283 171 1.1 216 15 0.22 346.5

However, difiicultly volatile starting materials such as Table I showsthat catalyst A results in unsaturated sperm oil can also behydrogenated with good results. fatty alco o s high iodine numbers and alow p The addition of lower alcohols causes the fatty alcohol 1 of"21115715911163: h 1 h to eva orate ver ra idl whereb the catal st isstill or companson wlt pnor art cata ysts .anot er Th y d y t g h t d ttron of the catalyst tablets were reduced with hydrogen Preserve 6 movea van ages 0 t 6 pm ma 6 ca in two stages, 280 C. at atmosphericpressures and then lysts of the invention do not depend upon theconcomitant at 260 mm. pressure to form catalyst B. A third portion useof aliphatic alcohols of 1 to 4 carbon atom of the catalyst tablets werefirst sintered at 780 C. in

In the following examples there are described Several air at atmosphericpressure and reduced as with catalyst f d t t t t th H B to formcatalyst C. The said catalysts were used in the Pre f em men S O 1 m e ehydrogenation of methyl oleate having an iodine number ever, t Should beunderstood that the lhventloh 13 not of 86 at 3 different temperaturesand the results are reintended to be limited to the specificembodiments. ported in Table II.

TABLE II yq Solidm Percent of tihiffi? H drox g i H d r i ci 1n Catalystture, C, I.N. S.N. ri umb r p C, cai bdiis is r fi er h ign es B 280 90.2 5. 8 s4. 0 3 3. a 14. 2. 38 290 92. 3 6; 9 so. 4 -4. 5 7. 1 2.0 300100 2. 8 39. 5 -7 14. 5 18 2. 5

C 280 85.1 26. 8 99 6 3. 1 26 0. 66 290 so. a 2. a 71 7. 4 a2 0. 9 30090.8 1. 4 s1 1 10.6 34 8.8

Example I The results of Table II show that the catalysts were 1 ofpowdery commercial Zinc Oxide and 1 kg of notefiective since aside fromsome olefinic hydrocarbons, amorphous aluminum hydroxide with a looseweight of only a httlle unsaturated fatty alcohol was obtained with 520gm./l. were stirred with water and the resulting elt er cata powder wasvacuum filtered, dried, admixed with 2% Example H by weight of graphiteand pressed with 4 mm. tablets. k

A portion of the tablets were reduced with hydrogen 1 of mmiherclal zmcPxlde PP and 1 of at to form catalyst A While passing crystallizedalummum hydroxlde having a loose weight of through a stream f 50 to 200liters per hour f hydrogen 1,275 gm. per liter were processed into acatalyst accordunder atmospheric pressure. Catalyst A was used to hy-111g the Procedure for catalyst A of Example The drogenate the followingcommercial fatty esters: oleic resultmg Catalyst W511S used tohydrogehate the Starting acid-methyl ester, soya-fatty acid-methylester, and linmateria s of Example Iby the process of the said examseedfatty acid-methyl ester. ple. The results are shown in Table III.

TABLE III Percent of- Hydrotgenation H d Soligifi- H d T Conci em era-TOX GEL 1O Final products turn, C, I.N. S.N. n innbei point, C cafioti sisb ir i r d ig fi es a. Commercial oleyl alcohol. 283 85.4 1.3 214 40.32- 5 0,35 b. Commercial soya-aleohol mixture 281 1 4 1. 3 215 14. 50.21 8 163 1 7 214 13.5 0.75 as ple III TABLE VI Using the procedure ofExample I, 'y-aluminum oxide Percent and zmc oxide in a 1.2 ration wereused to form catalyst I Hydm Tram jugated tablets reduced in hydrogen at750 C. The said catalyst 5 Starting mate/m1 caYbOns 150m items was usedin the hydrogenation of the fatty acid esters of a Commercial Oleic acidmethyl ester 80 191 0.20 3 1. 3 Table IV to obtain unsaturated fattyalcohols of Table V. b. Commercial soya fatty acid methyl ester 102 0.050. 9 0. Commercial linseed fatty acid methyl 173 190 0. 05 11 1. 6

TABLE VII Percent of Hydrosolidifigenatlon cation Conjutempera- Hydroxypoint, Hydro- Transgated Final products ture, C. IN. S.N. number Ccarbons isomer dienes a. Commercial oleic alcohol 262 86. 4 1. 3 216 30. 33 6 1. 49 b. Commercial soya-alcohol mixture 262 140. 3 1. 6 212 140. 12 8 2. 9 0. Commercial linseed-alcohol mixture 272 183. 5 1 4 21313. 5 0. 10 26 4. 9

Examples V to VIII were carried out in an apparatus TABLE IV Per nt oicomprlsing a furnace of 14 liter capacity and a gas circu- Ce lationpump. The through-put difiered each time and is indicated each time justas the dilution of the oleic acid Hydro- Transugated Starting materialI.N. S.N. carbon isome dimes ester with alcohol 18 1nd1cated each tlme.The Zn-Al catar 4 l i I a. cgnilemialoleic acid 80 191 Q20 3 L3 2.) lystwas prepared according to Example I A.

me y ester b. Commercial soya fatty 0 9 Example V methylester 132 192 0The starting material was oleic acid methyl ester hav- TABLE V Percentof- Hydro- Solidifigenation cation Conjutempera- Hydroxy point, Hydro-Transgated Final products ture, C I N. S N number carbons isomer dienesa. Commercial oleyl alcohol 295 86.5 1.7 212 3 0. 5 0.87 b. Commercialsoya-alcohol mixt 295 136. 2 1. 6 213 13.5 0.32 13 3.9

Table V shows that catalysts prepared with aluminum oxide at hightemperatures give equally satisfactory results.

ing an iodine number of 82 and a saponification number 40 of 192. Theresult are summarized in Table VIII.

TABLE VIII Dilu- Percent of Hydro- (with genation Solidifi- Con-Throughmethtempera- Hydroxy cation Hydrojugated Test No put, l./h. ture,C. I N S.N number point, C. carbons dienes Example IV Example VI 4.26kg. of Al (SO -18H O (chemically pure) were dissolved in 30 liters ofwater and 7 liters of 10% aqueous ammonia were added with stirring atroom temperature. The freshly precipitated aluminum hydroxide was vacuumfiltered and was suspended in water together with 1 kg. of commercialzinc oxide. The suspension was washed repeatedly with water until thewash waters were Instead of the oleic acid methyl ester used in ExampleV, an oleicacid ester of isopropanol having an iodine 60 summarized in Table IX.

TABLE IX Hydro- Percent 01- genation Solidifi- Throughtempera- Hydroxycation Hydro- Transput, l./h. Dilution ture, C. LN. S.N. number point,C. carbons isomer 5 1:2 methanol 283 95.6 1.4 209 2 0.39 17 1.7 1:0 27590.0 1.2 211 4 0.49 23 5 1:2is0propan0l 277 92.5 1.2 210 3 0.62 20 freeof sulfate. After drying, the catalyst was put in tablet form andsintered for 2 hours in a hydrogen stream at 750 C. as in Example I. Thetablets showed ahigh mechanical firmness after sintering. The catalystswere used in the hydrogenation of the esters of Table VI using theExamples V and VI show that the selective hydrogenation of the estergroup with the catalysts of the invention is successful at varyingdilutions with methanol and different throughputs without any essentiallessening of quality although as can be seen from the hydrocarboncontent method of Example I to obtain alcohols of Table VII. lowerthroughput and dilution with methanol yields a better finalproduct.Example VI also shows-that isopropanol esters of unsaturated fattyesters can be selectively hydrogenated with and without diluents.

Example VII 7 Using the Zn-Al catalyst of Example 'I-A, free oleic acidhaving an iodine number of 92 and a saponification number of 205 wasselectively hydrogenated with good success as can be seen from Table X.

2. The process of claim 1 wherein the alcohol is methanol. v

3. The process of claim 1 wherein the starting material is the methylester of the unsaturated fatty acids.

4. The process of claim 3 wherein the hydrogenation i's eifectedin thepresence of an aliphatic alcohol of 1 to 4 carbon atoms.

5. The process of claim 1 wherein the reducing atmosphere for thepretreatment of the catalyst is selected from TABLE X Hydro-Percenb-ofgen-ation Solidifi- Dilution tcmpera- Hydroxy cation Hydro-Trans- Throughput, l./l1. (methanol) ture, C. LN. S.N. Number point, C.carbons isomer Example VIII Sperm oil, an example of esters from fattyacids and long-chain alcohols, was also selectively hydrogenated withthe catalyst of Example VII and the 'resultsare summarized in the TableXI.

TABLE XI Percent trans-isomer 5 The sperm oil had an iodine number of75.5 and a saponification number of 138 for Table XI.

Various modifications of the catalyst composition and hydrogenationprocess of the invention may be made without departing from the spiritor scope thereof, and his to be understood that the invention is to belimited only as defined in the appended claims.

We claim:

1. A process for the preparation of unsaturated fatty alcohols of 8 to22 carbon atoms which comprises continuously hyd'rogenating a memberselected from the group consisting of unsaturated fatty acids of 8 to 22carbon atoms and their esters with monovalent aliphatic alcohols of 1 to18 carbon atoms at temperatures of 250 pheres, the amount of hydrogenbeing 10 to 100 Nm. per liter of starting material, in the presence of azinc-aluminum oxygen containing catalyst which has been pretreated at 40to 1000 C. in a reducing atmosphere.

- the group consisting of hydrogem'carbon monoxide and mixtures ofhydrogen and carbon monoxide prepared 20 from methanol vapor.

References Cited v N UNITED STATES PATENTS 1,746,782 2/1930 Lazier252-468 1,900,829 3/1933 Lusby 252-468 2,094,127 9/1937 Lazier 260-638 A2,205,141 6/1940 .Heard 252--468 2,239,000 4/1941 Groombridge et al.252-468 2,279,198 4/1942 Huppke 252-463 2,512,653 6/1950 Kapecki 252-4682,623,020 12/1952- Gilbert 252463 2,876,265 3/ 1959 Braconier et a1.260-638 A 2,960,460 11/1960 Ryes et a1 252-468 3,107,146 10/1963 Sauaki23-151 FOREIGN PATENTS 1,228,603 11/1966 Germany 260-638 A 1,185,589l/1965 Germany 252-463 558,565 6/1958 Canada 260-638 A 1,487,277 5/1967France 260-638 A 1,111,196 4/1968 Great Britain 260-638 A to 330 C. anda hydrogen pressure of to 500 atmos- Primary Examiner J. E. EVANS,Assistant Examiner US. 01. X.R.-

